Dulce was last seen at a Bridgeton, New Jersey park the afternoon of Sept. 16.
Dulce and her 3-year-old brother were playing while their mother sat in her car with an 8-year-old relative, but her son soon ran to the car crying and pointed to the area where he last saw his sister.
"We will never give up on you, Dulce Maria. And we are asking you, the public, not to give up on her," said a family spokesperson earlier this week.
On Sunday, a group searched the park and the surrounding areas for any sign of the missing child.
There is a $52,000 reward being offered in the case.
Police recently released a sketch of a man they describe as a possible witness.
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